// Copyright 2014 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef CONTENT_BROWSER_TRACING_ETW_TRACING_AGENT_H_
#define CONTENT_BROWSER_TRACING_ETW_TRACING_AGENT_H_

#include <memory>

#include "base/bind.h"
#include "base/macros.h"
#include "base/memory/ref_counted_memory.h"
#include "base/threading/thread.h"
#include "base/trace_event/tracing_agent.h"
#include "base/values.h"
#include "base/win/event_trace_consumer.h"
#include "base/win/event_trace_controller.h"

namespace base {
template <typename Type>
struct DefaultSingletonTraits;
}

namespace content {

class EtwTracingAgent
    : public base::win::EtwTraceConsumerBase<EtwTracingAgent>,
      public base::trace_event::TracingAgent {
public:
    // base::trace_event::TracingAgent implementation.
    std::string GetTracingAgentName() override;
    std::string GetTraceEventLabel() override;
    void StartAgentTracing(const base::trace_event::TraceConfig& trace_config,
        const StartAgentTracingCallback& callback) override;
    void StopAgentTracing(const StopAgentTracingCallback& callback) override;

    // Retrieve the ETW consumer instance.
    static EtwTracingAgent* GetInstance();

private:
    // This allows constructor and destructor to be private and usable only
    // by the Singleton class.
    friend struct base::DefaultSingletonTraits<EtwTracingAgent>;

    // Constructor.
    EtwTracingAgent();
    ~EtwTracingAgent() override;

    void AddSyncEventToBuffer();
    void AppendEventToBuffer(EVENT_TRACE* event);

    // Static override of EtwTraceConsumerBase::ProcessEvent.
    // @param event the raw ETW event to process.
    friend class base::win::EtwTraceConsumerBase<EtwTracingAgent>;
    static void ProcessEvent(EVENT_TRACE* event);

    // Request the ETW trace controller to activate the kernel tracing.
    // returns true on success, false if the kernel tracing isn't activated.
    bool StartKernelSessionTracing();

    // Request the ETW trace controller to deactivate the kernel tracing.
    // @param callback the callback to call with the consumed events.
    // @returns true on success, false if an error occurred.
    bool StopKernelSessionTracing();

    void OnStopSystemTracingDone(
        const StopAgentTracingCallback& callback,
        const scoped_refptr<base::RefCountedString>& result);

    void TraceAndConsumeOnThread();
    void FlushOnThread(const StopAgentTracingCallback& callback);

    std::unique_ptr<base::ListValue> events_;
    base::Thread thread_;
    TRACEHANDLE session_handle_;
    base::win::EtwTraceProperties properties_;

    DISALLOW_COPY_AND_ASSIGN(EtwTracingAgent);
};

} // namespace content

#endif // CONTENT_BROWSER_TRACING_ETW_TRACING_AGENT_H_
